There are several locations on the exterior of a building that are vulnerable to penetration by moisture unless the exterior surface is properly sealed to prevent the moisture from entering the building interior and damaging walls and other interior structures. The locations that are especially vulnerable to moisture penetration include those places where different materials are joined together, such as, for example, the joints between the building exterior walls and windows or doors. Exterior siding material, by itself, cannot be installed tightly enough at such joints to produce a moisture proof seal. Once the exterior siding material has been completely installed, these joints may be filled with a waterproof sealing material, such as caulk, to keep moisture away from the interior walls. However, available caulking materials have a limited effective life and eventually lose their sealant capability and must be replaced.
Some types of exterior building siding materials, for example, vinyl siding and aluminum siding that are made to simulate wood clapboard siding, have configurations that tend to cause water to collect behind the siding, particularly if it has not been installed or caulked carefully. Moisture can then easily penetrate into the building interior walls and other structures. Caulking the joints between the siding and the window or door trim is helpful in preventing water collection and moisture penetration. However, if the caulking is improperly applied or cracks as it ages, the water collection and moisture penetration problems return.
The prevention of water damage around window frames, door frames and similar structures has been addressed by the prior art. For example, U.S. Pat. No. 4,555,882 to Moffitt et al. discloses a moisture guard for inhibiting water damage to the interior of a home or building caused by moisture, leaks, rain or snow accumulating at door frames, window frames and the like. This device is made of metal and plastic and has a Z-shaped cross-sectional configuration so that it may be positioned under and adjacent to the sill of a window frame or door frame to cover the sill. This moisture guard design, however, does not extend far enough beyond the window frame to cooperate with the siding configuration to direct moisture that might collect behind the exterior siding away from the interior wall. Additionally, the design of this moisture guard is more complex than is necessary to achieve the desired results.
U.S. Pat. No. 1,636,365 to Hokanson discloses a metallic window flashing formed with ribs designed to fit into grooves in the window facing. This particular kind of window flashing is limited in use to the double sash or double hung window design described in the Hokanson patent. More contemporary window styles, as well as double hung windows made of materials other than wood, require a flashing with a different configuration from that shown by Hokanson.
U.S. Pat. Nos. 4,966,819 to Schatz et al. and 5,018,333 to Bruhm disclose flashings for skylights or roof windows. The Schatz et al. patent discloses the formation of a water-tight transition configured to fit under the roof tiles with a lead apron covered with a layer of aluminum to prevent cracks in the lead. The Bruhm patent discloses a skylight flashing formed of four flanged and lapping panels made of an elastomeric material to form a weathertight seal. Neither of these patents suggests a flashing device that could be used to provide a watertight seal around a vertical window or door opening which also functions cooperatively with the siding material to direct water to the exterior of the siding.
U.S. Pat. No. 5,072,552 to Sauder describes a corner flashing device which provides a watertight seal. However, this flashing device is specifically designed to include a base and an upstanding adjustable portion so that the flashing can be used to prevent moisture penetration at the corners of such roof structures as chimneys and dormers and is not designed to cooperate with an exterior siding material to divert water to the exterior of the siding.
The use of a metal flashing piece for preventing water from accumulating behind aluminum siding has been suggested in conjunction with the installation of aluminum siding. An early installation guide for the installation of aluminum siding directed the installer to cut, freehand, a piece of flashing from metal coil stock flashing material of a suitable size and shape and position it at a window corner under a siding receiving channel and over the top of the siding panel below the window. The method of flashing a window or door corner described in this installation guide would be an effective way to prevent water from getting behind aluminum siding if it was followed correctly. However, because the preparation of a proper flashing piece requires the installer not only to have available the required metal flashing stock material but also to cut this material to the correct size and configuration to fit securely about a right angle corner structure, the installation of such corner flashing pieces has largely been ignored by siding installers. Consequently, the difficulty and inconvenience of first individually hand-making and then properly installing corner flashing while siding installation was in progress has resulted in no flashing being installed, which, in turn, has caused water damage at window and door corners where the siding joint was not sealed by a flashing material.
The prior art has failed, therefore, to provide a readily available, simple, unitary flashing device configured and formed of a material which allows it to be easily installed adjacent to a window or door frame in conjunction with the installation of exterior siding both to provide an effective watertight seal and to direct water away from under the siding to the building exterior. A need exists for such a flashing device.